This invention relates to a novel collector composition useful for the recovery of metal-containing sulfide minerals and sulfidized metal-containing oxide minerals from ores by froth flotation.
Flotation is a process of treating a mixture of finely divided mineral solids, e.g., a pulverulent ore, suspended in a liquid whereby a portion of such solids is separated from other finely divided mineral solids, e.g., clays and other like materials present in the ore, by introducing a gas (or providing a gas in situ) in the liquid to produce a frothy mass containing certain of the solids on the top of the liquid, and leaving suspended (unfrothed) other solid components of the ore. Flotation is based on the principle that introducing a gas into a liquid containing solid particles of different materials suspended therein causes adherence of some gas to certain suspended solids and not to others and makes the particles having the gas thus adhered thereto lighter than the liquid. Accordingly, these particles rise to the top of the liquid to form a froth. The phenomena which makes flotation a particularly valuable industrial operation appear to be largely associated with selective affinity of the surface of particulated solids, suspended in a liquid containing entrapped gas, for the liquid on the one hand, the gas on the other.
Various flotation agents have been admixed with the suspension to improve the frothing process. Such added agents are classed according to the function to be performed and include collectors such as xanthates, thionocarbamates and the like; frothers which impart the property of forming a stable froth, e.g., natural oils such as pine oil and eucalyptus oil; modifiers such as activators to induce flotation in the presence of a collector, e.g., copper sulfate; depressants, e.g., sodium cyanide, which tend to prevent a collector from functioning as such on a mineral which it is desired to retain in the liquid, and thereby discourage a substance from being carried up and forming a part of the froth; pH regulators to produce optimum metallurgical results, e.g., lime, soda ash and the like. The specific additives are selected for use according to the nature of the ore, the mineral sought to be recovered and the other additaments which are to be used in combination therewith.
The flotation principle is applied in a number of mineral separation processes among which is the selective separation of such metal sulfide minerals as those containing copper, zinc, lead, nickel, molybdenum and other metal sulfide minerals containing primarily iron such as pyrite and pyrrhotite.
Once recovered, the metal-containing minerals are converted to the more useful pure metal state, often by a smelting process. Such smelting processes can result in the formation of volatile sulfur compounds. These volatile sulfur compounds are often released to the atmosphere through smokestacks, or are removed from such smokestacks by expensive and elaborate scrubbing equipment.
Among collectors commonly used for the recovery of metal-containing sulfide minerals or sulfidized metal-containing oxide minerals are xanthates, dithiophosphates, and thionocarbamates. Unfortunately, these materials are not particularly selective in the recovery of sulfide or sulfidized oxide minerals. For example, many nonferrous metal containing sulfide minerals or metal-containing oxide minerals are found naturally in ores which also consist of sulfide minerals containing primarily iron. When these iron-containing sulfide minerals are recovered in flotation processes along with the non-ferrous metal-containing sulfide minerals and sulfidized metal-containing oxide minerals, there is excess sulfur present which is released in the smelting processes resulting in an undesirably high amount of sulfur present during the smelting operations. The xanthates, thionocarbamates, and dithiophosphates do not selectively recover nonferrous metal-containing sulfide minerals in the presence of iron-containing sulfide minerals. On the contrary, such collectors collect and recover all metal-containing sulfide minerals.
Therefore, it would be highly desirable to provide a composition which is capable of selectively recovering, at good recovery rates and selectivities, a broad range of metal-containing minerals from mineral ores, including the metal-containing sulfide minerals or sulfidized metal-containing oxide minerals in the presence of sulfide minerals containing primarily iron.